JP2021036484A - Secondary battery and manufacturing method of the secondary battery - Google Patents

Abstract

To provide a secondary battery which can suppress preferably a local electrode material layer from cracking or peeling in an electrode with a separator, having a bend part.SOLUTION: According to the present invention, a secondary battery comprises: a single electrode with a separator, in which one electrode and the separator is integrally structured; and at least two other electrodes having a different polarity from that of one electrode. The electrode with the separator alternately includes a non-bend part and a bend part continuous to the non-bend part, and the non-bent part and the other electrode are alternately arranged along a lamination direction. The bend part includes only a collector of the one electrode and the separator, which are bent, respectively.SELECTED DRAWING: Figure 1

Description

The present invention relates to a secondary battery and a method for manufacturing the secondary battery.

Secondary batteries that can be repeatedly charged and discharged have been used for various purposes. For example, a secondary battery is used as a power source for electronic devices such as smartphones and notebook computers.

In recent years, with the increasing demand for thinner and smaller electronic devices, there is a demand for thinner, smaller and higher capacity secondary batteries. In order to meet such a demand, Patent Document 1 and Patent Document 2 describe a single electrode with a separator in which one electrode and a separator form an integral structure, and at least two other electrodes having different polarities from the one electrode. A secondary battery that combines the above is shown. In one aspect, the separator-equipped electrode has a continuous meandering structure (that is, a zigzag structure) as a whole (see Patent Document 1). In another aspect, the electrode with a separator has a continuous winding structure with respect to at least two other electrodes as a whole (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-103082 Japanese Unexamined Patent Publication No. 2013-524431

Here, the inventors of the present application consider that the electrode with a separator has a continuous meandering structure (that is, a zigzag structure) as a whole, and / or a continuous winding structure with respect to at least two other electrodes as a whole. It has been found that the following problems can occur when having (see FIG. 10).

Hereinafter, a case where the electrode 100'with a separator has a continuous meandering structure as a whole will be taken as an example. In this case, the electrode with separator 100'may have a curved portion 101'locally due to the fact that the electrode with separator 100'has a meandering structure. Since the curved portion 101'has a curved shape, the separator 50'and the electrode (for example, the negative electrode 10B'), which are components of the electrode with a separator located at the curved portion 101', have a curved shape. Will have. More specifically, the separator 50'located at the curved portion 101', the current collector (for example, the negative electrode current collector 11B') which is a component of the electrode (for example, the negative electrode 10B'), and the electrode material layer (for example, the negative electrode material). The layer 12B') will have a curved shape.

When the electrode material layer located at the curved portion 101'(for example, the negative electrode material layer 12B') has a curved shape, tensile stress may be generated in the electrode material layer located at the curved portion 101'due to the curved shape. The generation of such stress may lead to cracking of the electrode material layer starting from the generation point and / or local peeling of the electrode material layer. Therefore, there is a possibility that a short circuit may occur when a voltage is applied, starting from the cracked portion α'and / or the peeled portion of the electrode material layer of the electrode material layer. Therefore, the electrode provided with the electrode material layer having the cracked portion α'and / or the peeled portion may not function suitably as a component of the secondary battery. As a result, the secondary battery including the electrode as a whole may not be able to suitably exhibit the desired battery characteristics.

The present invention has been made in view of such circumstances. That is, a main object of the present invention is to provide a secondary battery and a method for manufacturing the same, which can suitably suppress cracking or peeling of a local electrode material layer in an electrode with a separator having a curved portion.

In order to achieve the above object, in one embodiment of the present invention,
A secondary battery comprising a single electrode with a separator in which one electrode and a separator form an integral structure, and at least two other electrodes having different polarities from the one electrode.
The electrode with a separator alternately has a non-curved portion and a curved portion continuous with the non-curved portion, and the non-curved portion and the other electrode are alternately arranged along the stacking direction, and
A secondary battery is provided in which the curved portion has only the current collector of the one electrode and the separator, each of which is curved.

Further, in order to achieve the above object, in one embodiment of the present invention,
A method for manufacturing a secondary battery, comprising a single electrode with a separator in which one electrode and a separator form an integral structure, and at least two other electrodes having different polarities from the one electrode.
Including locally bending the elongated electrode with a separator.
Provided is a manufacturing method in which only the current collector of the one electrode and the separator are positioned at a portion where the elongated electrode with a separator is locally curved.

According to one embodiment of the present invention, the electrode with a separator having a curved portion can suitably suppress local cracking or peeling of the electrode material layer.

FIG. 1 is a schematic view of an electrode assembly including an electrode with a separator having a curved portion. FIG. 2 is a schematic view of an electrode assembly provided with electrodes having a meandering shape with a separator. FIG. 3 is a schematic view of an electrode assembly provided with an electrode with a separator which is wound in one direction. FIG. 4 is a schematic view of an electrode assembly including an electrode with a separator composed of a combination of a unidirectionally wound form and a meandering form. FIG. 5 is a schematic view of a mode in which a long electrode with a separator is locally curved. FIG. 6A is a schematic view of one aspect of forming an electrode with a long separator. FIG. 6B is a schematic view of another aspect of forming an electrode with a long separator. FIG. 6C is a schematic view of still another aspect of forming an electrode with a long separator. FIG. 6D is a schematic view of yet another aspect of forming an electrode with a long separator. FIG. 7 is a schematic view of an aspect at the start of formation of an electrode assembly having an electrode with a separator having a meandering shape. FIG. 8 is a schematic view of a mode in which an electrode assembly having a meandering electrode with a separator is being formed. FIG. 9 is a cross-sectional view schematically showing the basic configuration of the electrode constituent layer. FIG. 10 is a schematic diagram showing a technical problem found by the inventor of the present application.

Before explaining the method for manufacturing a secondary battery according to an embodiment of the present invention, the basic configuration of the secondary battery will be described. The term "planar view" as used herein refers to a state in which the object is viewed from above or below along the thickness direction based on the stacking direction of the electrode materials constituting the secondary battery. Further, the "cross-sectional view" referred to in the present specification is a state when viewed from a direction substantially perpendicular to the thickness direction based on the stacking direction of the electrode materials constituting the secondary battery.

[Basic configuration of secondary battery]
The present invention provides a secondary battery. The term "secondary battery" as used herein refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery of the present invention is not overly bound by its name, and for example, a "storage device" and the like can be included in the subject of the present invention. The secondary battery has a structure in which the electrode assembly and the electrolyte are housed and sealed inside the exterior body. In the present invention, the electrode assembly may have a structure including an electrode constituent layer including a positive electrode, a negative electrode, and a separator. Further, the exterior body may take the form of a conductive hard case or a flexible case (pouch or the like). When the outer body is in the form of a flexible case (pouch or the like), the positive electrode is connected to the external terminal for the positive electrode via the current collecting lead for the positive electrode. The external terminal for the positive electrode is fixed to the exterior body by the seal portion, and the seal portion prevents the electrolyte from leaking. Similarly, the negative electrode is connected to the negative electrode external terminal via the negative electrode current collecting lead. The external terminal for the negative electrode is fixed to the exterior body by the seal portion, and the seal portion prevents the electrolyte from leaking. The current collecting lead for the positive electrode connected to the positive electrode may have the function of the external terminal for the positive electrode, and the current collecting lead for the negative electrode connected to the negative electrode has the function of the external terminal for the negative electrode. May be equipped. When the outer body is in the form of a conductive hard case, the positive electrode is connected to the external terminal for the positive electrode via the current collecting lead for the positive electrode. The external terminal for the positive electrode is fixed to the exterior body by the seal portion, and the seal portion prevents the electrolyte from leaking.

The positive electrode 10A is composed of at least a positive electrode current collector 11A and a positive electrode material layer 12A (see FIG. 9), and the positive electrode material layer 12A is provided on at least one surface of the positive electrode current collector 11A. A drawer tab on the positive electrode side is positioned at a portion of the positive electrode current collector 11A where the positive electrode material layer 12A is not provided, that is, at the end of the positive electrode current collector 11A. The positive electrode material layer 12A contains a positive electrode active material as an electrode active material. The negative electrode 10B is composed of at least a negative electrode current collector 11B and a negative electrode material layer 12B (see FIG. 9), and a negative electrode material layer 12B is provided on at least one surface of the negative electrode current collector 11B. The negative electrode side drawer tab is positioned at a portion of the negative electrode current collector 11B where the negative electrode material layer 12B is not provided, that is, at the end of the negative electrode current collector 11B. The negative electrode material layer 12B contains a negative electrode active material as an electrode active material.

The positive electrode active material contained in the positive electrode material layer 12A and the negative electrode active material contained in the negative electrode material layer 12B are substances directly involved in the transfer of electrons in the secondary battery, and are mainly responsible for charge / discharge, that is, the battery reaction. It is a substance. More specifically, ions are brought to the electrolyte due to the "positive electrode active material contained in the positive electrode material layer 12A" and the "negative electrode active material contained in the negative electrode material layer 12B", and such ions are brought to the electrolyte with the positive electrode 10A and the negative electrode. It moves to and from 10B, and electrons are transferred to charge and discharge. The positive electrode material layer 12A and the negative electrode material layer 12B are particularly preferably layers capable of occluding and releasing lithium ions. That is, a secondary battery in which lithium ions move between the positive electrode 10A and the negative electrode 10B via an electrolyte to charge and discharge the battery is preferable. When lithium ions are involved in charging and discharging, the secondary battery corresponds to a so-called "lithium ion battery".

The positive electrode active material of the positive electrode material layer 12A is made of, for example, granules, and a binder (also referred to as “binding material”) is contained in the positive electrode material layer 12A for sufficient contact between particles and shape retention. Is preferable. Further, a conductive auxiliary agent may be contained in the positive electrode material layer 12A in order to facilitate the transfer of electrons that promote the battery reaction. Similarly, when the negative electrode active material of the negative electrode material layer 12B is composed of particles, for example, it is preferable that the negative electrode active material contains a binder for sufficient contact between particles and shape retention, and facilitates the transfer of electrons that promote the battery reaction. The conductive auxiliary agent may be contained in the negative electrode material layer 12B. As described above, the positive electrode material layer 12A and the negative electrode material layer 12B can also be referred to as a "positive electrode mixture layer" and a "negative electrode mixture layer", respectively, because of the form in which a plurality of components are contained.

The positive electrode active material is preferably a substance that contributes to the occlusion and release of lithium ions. From this point of view, the positive electrode active material is preferably, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material is preferably a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese and iron. That is, in the positive electrode material layer 12A of the secondary battery, such a lithium transition metal composite oxide is preferably contained as the positive electrode active material. For example, the positive electrode active material may be lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, or a part of the transition metal thereof replaced with another metal. Such a positive electrode active material may be contained as a single species, but may be contained in combination of two or more species. In a more preferred embodiment, the positive electrode active material contained in the positive electrode material layer 12A is lithium cobalt oxide.

The binder that can be contained in the positive electrode material layer 12A is not particularly limited, but is not particularly limited, but is a polyvinylidene fluoride, a bilinidene fluoride-hexafluoropropylene copolymer, and a bilinidene fluoride-tetrafluorotilene copolymer. And at least one selected from the group consisting of polytetrafluoroethylene and the like can be mentioned. The conductive auxiliary agent that can be contained in the positive electrode material layer 12A is not particularly limited, but is carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes and vapor phase. At least one selected from carbon fibers such as grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned. In a more preferred embodiment, the binder of the positive electrode material layer 12A is polyvinylidene fluoride, and in another more preferred embodiment, the conductive auxiliary agent of the positive electrode material layer 12A is carbon black. In a more preferred embodiment, the binder and conductive aid of the positive electrode material layer 12A are a combination of polyvinylidene fluoride and carbon black.

The negative electrode active material is preferably a substance that contributes to the occlusion and release of lithium ions. From this point of view, the negative electrode active material is preferably, for example, various carbon materials, oxides, lithium alloys, or the like.

Examples of various carbon materials for the negative electrode active material include graphite (natural graphite, artificial graphite), soft carbon, hard carbon, and diamond-like carbon. In particular, graphite is preferable because it has high electron conductivity and excellent adhesion to the negative electrode current collector 11B. Examples of the oxide of the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide and the like. The lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium, for example, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of a metal such as La and lithium. It is preferable that such an oxide is amorphous as its structural form. This is because deterioration due to non-uniformity such as grain boundaries or defects is less likely to occur. In a more preferred embodiment, the negative electrode active material of the negative electrode material layer 12B is artificial graphite.

The binder that can be contained in the negative electrode material layer 12B is not particularly limited, but is at least one selected from the group consisting of styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide-based resin, and polyamide-imide-based resin. Seeds can be mentioned. In a more preferred embodiment, the binder contained in the negative electrode material layer 12B is styrene-butadiene rubber. The conductive auxiliary agent that can be contained in the negative electrode material layer 12B is not particularly limited, but is carbon black such as thermal black, furnace black, channel black, ketjen black and acetylene black, graphite, carbon nanotubes and vapor phase. At least one selected from carbon fibers such as grown carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives can be mentioned. The negative electrode material layer 12B may contain a component derived from a thickener component (for example, carboxylmethyl cellulose) used at the time of manufacturing the battery.

In a more preferred embodiment, the negative electrode active material and the binder in the negative electrode material layer 12B are a combination of artificial graphite and styrene-butadiene rubber.

The positive electrode current collector 11A and the negative electrode current collector 11B used for the positive electrode 10A and the negative electrode 10B are members that contribute to collecting and supplying electrons generated by the active material due to the battery reaction. Such a current collector may be a sheet-shaped metal member and may have a perforated or perforated form. For example, the current collector may be a metal leaf, a punching metal, a net, an expanded metal, or the like. The positive electrode current collector 11A used for the positive electrode 10A is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel and the like, and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector 11B used for the negative electrode 10B is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel and the like, and may be, for example, a copper foil.

The separator 50 is a member provided from the viewpoint of preventing a short circuit due to contact between the positive and negative electrodes and retaining the electrolyte. In other words, it can be said that the separator 50 is a member that allows ions to pass through while preventing electronic contact between the positive electrode 10A and the negative electrode 10B. Preferably, the separator 50 is a porous or microporous insulating member and has a film morphology due to its small thickness. Although only an example, a microporous polyolefin membrane may be used as the separator. In this regard, the microporous membrane used as the separator 50 may contain, for example, only polyethylene (PE) or polypropylene (PP) as the polyolefin. Furthermore, the separator 50 may be a laminate composed of a "microporous membrane made of PE" and a "microporous membrane made of PP". The surface of the separator may be covered with an inorganic particle coat layer and / or an adhesive layer or the like. The surface of the separator may have adhesiveness.

From the viewpoint of further improving the handling of the electrode, it is preferable that the separator 50 and the electrode (positive electrode 10A / negative electrode 10B) are adhered to each other. The separator 50 and the electrode are bonded by using an adhesive separator as the separator 50, applying an adhesive binder on the electrode material layer (positive electrode material layer 12A / negative electrode material layer 12B), and / or thermocompression bonding. Can be done. Examples of the adhesive that provides adhesiveness to the separator 50 or the electrode material layer include polyvinylidene fluoride, an acrylic adhesive, and the like.

The electrolyte assists the movement of metal ions released from the electrodes (positive electrode 10A, negative electrode 10B). The electrolyte may be an electrolyte containing a "non-aqueous" solvent such as an organic electrolyte and an organic solvent and a solute, or an "aqueous" electrolyte containing water. The secondary battery is preferably a non-aqueous electrolyte secondary battery in which a “non-aqueous” electrolyte is used as the electrolyte. The electrolyte may have a form such as liquid or gel (note that the "liquid" non-aqueous electrolyte is also referred to as "non-aqueous electrolyte solution" in the present specification).

As a specific solvent for the non-aqueous electrolyte, one containing at least carbonate is preferable. Such carbonates may be cyclic carbonates and / or chain carbonates. Although not particularly limited, the cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC) and vinylene carbonate (VC). be able to. Examples of the chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC). In a preferred embodiment, a combination of cyclic carbonates and chain carbonates is used as the non-aqueous electrolyte, for example a mixture of ethylene carbonate and diethyl carbonate. Further, as a specific solute of the non-aqueous electrolyte, Li salts such as _{LiPF 6} and LiBF _{4 are preferably used.} Further, as a specific solute of the non-aqueous electrolyte, Li salts such as _{LiPF 6} and LiBF _{4 are preferably used.}

As the positive electrode current collector reed and the negative electrode current collector reed, any current collector reed used in the field of secondary batteries can be used. Such a current collecting lead may be composed of a material in which electron transfer can be achieved, and is composed of a conductive material such as aluminum, nickel, iron, copper, or stainless steel. The positive electrode current collecting lead is preferably made of aluminum, and the negative electrode current collecting lead is preferably made of nickel. The form of the positive electrode current collecting lead and the negative electrode current collecting lead is not particularly limited, and may be, for example, a wire or a plate.

As the external terminal, any external terminal used in the field of secondary batteries can be used. Such external terminals may be made of a material in which electron transfer can be achieved, and are usually made of a conductive material such as aluminum, nickel, iron, copper, stainless steel. The external terminal 5 may be electrically and directly connected to the substrate, or may be electrically and indirectly connected to the substrate via another device. Not limited to this, the positive electrode current collecting lead connected to each of the plurality of positive electrodes may have the function of the positive electrode external terminal, and the negative electrode current collecting lead connected to each of the plurality of negative electrodes. The lead may have the function of an external terminal for a negative electrode.

The exterior body may have the form of a conductive hard case or a flexible case (pouch or the like) as described above.

The conductive hard case consists of a main body and a lid. The main body is composed of a bottom portion and a side surface portion constituting the bottom surface of the exterior body. The main body and lid are sealed after accommodating the electrode assembly, electrolyte, current collector leads and external terminals. The sealing method is not particularly limited, and examples thereof include a laser irradiation method. As the material for forming the main body and the lid, any material that can form a hard case type exterior body can be used in the field of the secondary battery. Such a material may be any material in which electron transfer can be achieved, including conductive materials such as aluminum, nickel, iron, copper and stainless steel. The dimensions of the main body and the lid are mainly determined according to the dimensions of the electrode assembly. For example, when the electrode assembly is housed, the dimensions are such that the movement (displacement) of the electrode assembly inside the exterior body is prevented. It is preferable to have. By preventing the electrode assembly from moving, the electrode assembly is prevented from being destroyed, and the safety of the secondary battery is improved.

The flexible case is composed of a soft sheet. The soft sheet may have sufficient softness to achieve bending of the sealing portion, and is preferably a plastic sheet. The plastic sheet is a sheet having a property of maintaining deformation due to an external force when it is removed after applying an external force. For example, a so-called laminated film can be used. A flexible pouch made of a laminated film can be manufactured, for example, by laminating two laminated films and heat-sealing the peripheral portion thereof. The laminated film is generally a film in which a metal foil and a polymer film are laminated, and specifically, a three-layer structure composed of an outer layer polymer film / metal foil / inner layer polymer film is exemplified. The outer layer polymer film is for preventing damage to the metal foil due to permeation of moisture and the like and contact, and polymers such as polyamide and polyester can be preferably used. The metal foil is for preventing the permeation of moisture and gas, and a foil of copper, aluminum, stainless steel or the like can be preferably used. The inner layer polymer film protects the metal foil from the electrolyte stored inside and melts and seals the metal leaf at the time of heat sealing, and polyolefin or acid-modified polyolefin can be preferably used.

[Secondary battery of the present invention]
The secondary battery according to the embodiment of the present invention will be described below in consideration of the basic configuration of the secondary battery.

The inventor of the present application has diligently studied countermeasures for suitably suppressing local cracking or peeling of the electrode material layer in the electrode with a separator having a curved portion. As a result, the secondary battery of the present invention has been devised.

Hereinafter, terms used in the present specification will be defined prior to explaining the characteristic parts of the present invention. Hereinafter, terms used in the present specification will be defined prior to explaining the characteristic parts of the present invention. The "electrode with a separator" as used herein refers to an electrode in which the separator is adhered to the main surface of the electrode and the electrode and the separator have an integral structure. The "electrode with a separator having non-curved portions and curved portions alternately" referred to in the present specification is an electrode with a separator in which curved portions are formed at predetermined intervals, and is a structure of an electrode assembly which is a finished product. Refers to the element. The "long-shaped electrode with a separator extending in one direction" as used herein is an electrode with a separator used in the process of manufacturing an electrode assembly, and extends in one direction along a longitudinal axis. Refers to those with a relatively large length dimension.

As used herein, the "non-curved portion of the electrode with a separator" refers to a component of the electrode with a separator that is not curved, and refers to, for example, a portion that extends linearly in one direction. Further, the "non-curved portion of the electrode with a separator" referred to in the present specification is located between one curved portion and the other curved portion of the electrode with a separator, and is configured to be continuous with the end portion of each curved portion. Refers to what has been done. The "curved portion of the electrode with a separator" as used herein refers to a portion that is a component of the electrode with a separator and has a curved shape, for example, a portion having a semicircular or semi-elliptical shape. As used herein, the term "one electrode" refers to an electrode that is a component of an electrode with a separator. The "other electrode" as used herein refers to an electrode having a polarity different from that of the electrode included in the electrode with a separator, and which is relatively shorter than the electrode with a separator and extends in only one direction. The "side portion of the other electrode" as used herein refers to the exposure of the electrodes when the main surface of the positive electrode and the main surface of the negative electrode are laminated so as to face each other with the separator sandwiched in the laminating direction. Refers to the end face.

The “non-formed portion of the electrode material layer” as used herein refers to a portion in which the electrode material layer is not formed. The term "separator / current collector forms a meandering form" as used herein means a form in which the separator / current collector winds to the left and right like a serpent in a cross-sectional view or a plan view, a zigzag form, or a zigzag shape. It means to form the form of. In the present specification, "a form in which only the current collector and the separator of one electrode are wound in one direction as a whole" is a component of the electrode with a separator so as to be wound around the other electrode in a broad sense. This refers to a form in which only the current collector and the separator of one of the electrodes are wound in the same direction. As used herein, "only the current collector and separator of one electrode form a wound in one direction as a whole" means that one electrode has a curved portion and a non-curved portion in a narrow sense. Refers to a state in which only the current collector and the separator of the above are wound in one direction as a whole. As used herein, "locally curving an electrode with a long separator extending in one direction" means having a long separator extending in one direction during the manufacturing of an electrode assembly. Refers to selectively or partially bending a limited portion of the entire electrode. The "non-coated portion of the electrode material layer" as used herein refers to a portion in which the electrode material layer is not coated on the main surface of the plate-shaped metal leaf serving as a current collector. In the present specification, "only the current collector and the separator of one electrode are continuous as a whole" means that the current collector and the separator of one electrode are each continuous when the electrode with the separator including the curved portion is viewed as a whole. It means that one end to the other end of is connected without interruption.

(Basic technical idea of the present invention)
As a countermeasure, the inventor of the present application has devised to remove the electrode material layer where local cracking or peeling may occur from the curved portion of the electrode with a separator. That is, the present invention has a technical idea that the electrode material layer does not exist in the curved portion of the electrode with a separator. According to such a technical idea, since the electrode material layer does not exist in the curved portion of the electrode with a separator, the occurrence of local cracking or peeling of the electrode material layer in the curved portion due to this is suitably suppressed. It becomes possible. Thereby, the original technical problem found by the present inventor can be solved. Details including other technical effects will be described below.

Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 is a schematic view of an electrode assembly 200 including an electrode 100 with a separator having a curved portion 101. The secondary battery according to the embodiment of the present invention has an electrode assembly 200 inside the exterior body. The electrode assembly 200 includes a single electrode with a separator 100 in which a plurality of one electrode (for example, a negative electrode 10B) and a separator 50 form an integral structure, and at least two other electrodes having polarities different from those of the one electrode (for example). Positive electrode 10A) and. The electrode 100 with a separator includes one electrode (for example, a negative electrode 10B) and two separators 50 facing each other arranged so as to sandwich the electrode. The other electrode includes a current collector (for example, positive electrode current collector 11A) and electrode material layers (for example, positive electrode material layer 12A) formed on both sides of the current collector, except for the outermost layer region of the electrode assembly 200. .. The other electrode has a current collector (for example, positive electrode current collector 11A) and an electrode material layer (for example, positive electrode material layer 12A) formed on one side of the current collector in the outermost layer region of the electrode assembly 200. Have.

The electrode 100 with a separator has a configuration in which a non-curved portion 102 and a curved portion 101 continuous with the non-curved portion 102 are alternately provided. The non-curved portion 102 is an electrode material layer forming portion of one of the electrodes (for example, the negative electrode 10B). Specifically, the non-curved portion 102 includes a current collector of one electrode (for example, a negative electrode current collector 11B) and electrode material layers (for example, a negative electrode material layer 12B) formed on both sides of the current collector. On the other hand, the curved portion 101 of the electrode 100 with a separator may be formed so as not to be in direct contact with the other electrode (for example, the positive electrode 10A) facing the other electrode while forming a curved shape.

Further, in the electrode assembly 200, as shown in FIG. 1, the non-curved portion 102 of the electrode with separator 100 and the other electrode (for example, the positive electrode 10A) are alternately arranged along the stacking direction. Specifically, the non-curved portion 102 and the other electrode are alternately arranged along the stacking direction so that the main surface region of the non-curved portion 102 and the main surface region of the other electrode are in opposite contact with each other. Has been done.

Characteristic part of the secondary battery of the present invention Here, unlike the conventional aspect, the curved portion 101 of the electrode 100 with a separator has a structure having only a current collector of one of the curved electrodes and a curved separator. I'm taking it. This structure is a feature of the present invention. This means that the curved portion 101 adopts a structure in which the electrode material layer (for example, the negative electrode material layer 12B) of one of the electrodes is not formed as an “electrode material layer non-formed portion”. From another point of view, this means that in the curved portion 101, only the negative electrode current collector 11B is positioned between the two separators 50 which are the components of the electrode with the separator. _{Further, the curved portion 101 is positioned at a portion where the side portion 10A 1} of the other electrode (for example, the positive electrode 10A) and the curved portion 101 face each other.

Based on this point, when the electrode 100 with a separator is viewed as a whole, only the current collector and the separator 50 of one electrode (for example, the negative electrode 10B) included in the electrode 100 with a separator form a continuous form as a whole. Become. On the other hand, when the electrode 100 with a separator is viewed as a whole, the electrode material layer (for example, the negative electrode material layer 12B) is positioned in the alternately formed non-curved portions 102 in the electrode 100 with a separator, and therefore, as a whole. It will be in an intermittent form.

It can be said that the curved portion 101 is a portion where tensile stress can be generated due to its form. However, in the present invention, since the electrode material layer is not formed on the curved portion 101, tensile stress is generated in the electrode material layer. It is possible to suppress this. Therefore, by suppressing the generation of tensile stress on the electrode material layer, it is possible to suitably suppress the occurrence of local cracking or peeling of the electrode material layer at the curved portion 101. Therefore, it is possible to suitably suppress the occurrence of a short circuit when a voltage is applied, starting from the cracked portion of the electrode material layer and / or the peeled portion of the electrode material layer. As a result, the electrode (for example, the negative electrode 10B) included in the separator-equipped electrode 100 can function suitably as a component of the secondary battery as a whole due to the suppression of the occurrence of such a short circuit. As a result, the secondary battery of the present invention can suitably exhibit desired battery characteristics.

Further, as described above, in the electrode assembly 200, the non-curved portion 102 of the electrode with separator 100 and the other electrode (for example, the positive electrode 10A) are alternately arranged along the stacking direction. The non-curved portion 102 has a structure including one electrode (for example, a negative electrode 10B) and separators 50 positioned on both main surfaces of the electrode. In the non-curved portion 102 of the electrode 100 with a separator, one electrode (for example, the negative electrode 10B) has a current collector (for example, the negative electrode current collector 11B) and electrode material layers (for example, the negative electrode) formed on both sides of the current collector. It has a structure including a material layer 12B). From the above, the positive electrode 10A and the negative electrode 10B are configured to face each other via the separator 50. Therefore, lithium ions can move between the positive electrode 10A and the negative electrode 10B through the electrolytic solution to preferably transfer electrons. That is, in order to preferably transfer electrons, it is sufficient that the positive electrode 10A and the negative electrode 10B face each other via the separator 50. This means that electrons can be suitably transferred even if the curved portion 101 of the electrode 100 with a separator does not have an electrode material layer (for example, a negative electrode material layer). That is, even if the curved portion 101 of the electrode 100 with a separator does not have an electrode material layer (for example, a negative electrode material layer), it is possible to provide a predetermined battery capacity.

If the curved portion 101 of the electrode 100 with a separator does not have an electrode material layer (for example, a negative electrode material layer), the volume of the electrode, specifically, the electrode material layer, is provided to the curved portion 101 as a whole. It is reduced compared to the case. From another point of view, although not shown in detail in the drawings, since the separator 50 can be said to be a non-rigid material due to its material properties, the thickness of the curved portion 101 is due to the absence of the electrode material layer. Can be relatively reduced.

From the above, in the present invention, it is possible to provide a predetermined battery capacity even if the curved portion 101 does not have an electrode material layer (for example, a negative electrode material layer), while the volume or thickness of the electrode 100 with a separator as a whole is increased. It can be reduced. This means that the battery capacity per unit volume will increase. Thereby, it is possible to further improve the energy density of the battery due to the increase in the battery capacity per unit volume. Further, since the thickness of the curved portion 101 can be reduced, the size of the electrode assembly 200 can be reduced, and the size of the exterior body, that is, the secondary battery can be reduced.

In one aspect of the present invention, the current collector (for example, the negative electrode current collector 11B) and the separator 50 of one of the continuous electrodes (for example, the negative electrode 10B) may have the following forms.

As described above, in the present invention, the curved portion 101 of the electrode 100 with a separator has a structure having only the current collector of one of the curved electrodes and the curved separator. As long as such a structure is adopted, the form of the current collector (for example, the negative electrode current collector 11B) and the separator 50 of one continuous electrode (for example, the negative electrode 10B) is not particularly limited. As an example, only the negative electrode current collector 11B and the separator 50 of the negative electrode 10B may form a meandering shape as a whole (see FIG. 2). That is, only the negative electrode current collector 11B and the separator 50 can adopt a zigzag structure as a whole. More specifically, "the above-mentioned electrode 100 with a separator has a structure in which curved portions 101 and non-curved portions 102 are continuously and alternately formed" and "a component of the electrode 100 with a separator". Considering the point that "only a certain negative electrode current collector 11B and the separator 50 form a meandering form as a whole", the following form is adopted. That is, the negative electrode current collector 11B and the separator 50 form a meandering shape as a whole while forming curved portions and non-curved portions alternately and continuously. This means that the negative electrode current collector 11B and the separator 50 do not form a meandering shape as a whole while forming only curved portions alternately and continuously. As another example, only the negative electrode current collector 11B and the separator 50 of the negative electrode 10B may be wound in one direction as a whole (see FIG. 3). More specifically, "the above-mentioned electrode 100 with a separator has a structure in which curved portions 101 and non-curved portions 102 are continuously and alternately formed" and "a component of the electrode 100 with a separator". Taking into consideration the fact that only a certain negative electrode current collector 11B and the separator 50 are wound in one direction as a whole, the following form is adopted. That is, the negative electrode current collector 11B and the separator 50 are wound in one direction as a whole while forming curved portions and non-curved portions alternately and continuously. This means that the negative electrode current collector 11B and the separator 50 do not form a form in which only the curved portions are alternately and continuously formed and wound in one direction as a whole.

Further, in one aspect of the present invention, the current collector (for example, the negative electrode current collector 11B) and the separator 50 of one continuous electrode (for example, the negative electrode 10B) preferably take the following forms (see FIG. 4).

Specifically, first, a portion in which only the current collector (for example, the negative electrode current collector 11B) and the separator 50 of one of the electrodes, which are the components of the electrode 100 with a separator, are wound in one direction. It is composed of X and a portion Y forming a meandering shape continuous with the portion X, and the portion X is positioned in the outermost region of the electrode assembly. This means that the outermost region of the electrode assembly is not positioned with the other electrode (for example, the positive electrode 10A), which is relatively short compared to the electrode 100 with a separator and extends only in one direction. ..

Secondly, when the portion X is viewed as a whole, the non-curved portion 102α located on the terminal end side of the electrode with separator 100 is positioned so as to be sandwiched between the other electrodes (for example, the positive electrode 10A). In this aspect, the non-curved portion 102α includes a current collector 11B and electrode material layers 12B formed on both main surfaces of the current collector 11B. That is, a double-sided electrode structure is adopted in the non-curved portion 102α located on the terminal end side of the electrode with separator 100. On the other hand, the non-curved portion 102β immediately before the non-curved portion 102α located on the outermost end side of the electrode with separator 100 is positioned in the outermost region of the electrode assembly 200. In this aspect, the non-curved portion 102β includes a current collector 11B and an electrode material layer 12B formed only on one main surface of the current collector 11B. That is, a "single-sided electrode structure" is adopted in the non-curved portion 102β of the electrode 100 with a separator.

Here, the electrode in the outermost layer region of the electrode assembly 200 has a single-sided electrode structure extending in one direction (a structure including a current collector and an electrode material layer formed only on one main surface of the current collector). Is generally taken. However, such a structure can cause the following problems.

Specifically, the electrode located in the outermost layer region of the electrode assembly is for obtaining a desired density after applying and drying the electrode material layer only on one main surface of the current collector extending in one direction. It is obtained by performing the pressure treatment of. The current collector is mainly composed of a metal foil, that is, a metal member, while the electrode material layer mainly contains an active material and a binder (polymer-based compound). That is, the types of constituent materials of the current collector and the electrode material layer are different from each other. The difference in the material types between the current collector and the electrode material layer is due to the difference in the degree of elongation of the current collector and the electrode material layer when the pressure treatment for obtaining the outermost layer electrode having a desired density is performed. Can be connected. Therefore, due to the difference in the degree of elongation, the electrode material is stretched relatively larger than the current collector during the pressurization treatment for obtaining the electrode (corresponding to the single-sided electrode) positioned in the outermost layer, and as a result, the electrode material is the most stretched. Warpage stress is likely to occur in the electrodes located in the outer layer. The generation of such warping stress can lead to warping of the electrode located in the outermost layer. The warp of the electrode positioned in the outermost layer may prevent the electrode positioned in the outermost layer from being suitably adhered to the separator positioned between the electrode in the inner region (corresponding to the double-sided electrode) in the configuration of the electrode assembly 200 as a whole. .. Therefore, there is a possibility that the electrode of the outermost layer does not function suitably as a component of the electrode assembly 200. As a result, the secondary battery including the electrode assembly 200 as a whole may not be able to suitably exhibit the desired battery characteristics.

In this regard, as described above, in this embodiment, (1) the other electrode of the single-sided electrode structure extending in only one direction (for example, the positive electrode 10A) is not positioned as the outermost layer electrode. This means that the electrode that is prone to warpage does not exist in the outermost layer region of the electrode assembly 200.

Further, in this embodiment, (2) the portion to be the non-curved portion 102α (the portion located on the outermost end side of the electrode with separator 100) has a double-sided electrode structure, while the outermost portion of the electrode assembly 200. A "single-sided electrode structure" is adopted in the non-curved portion 102β positioned in the region (the portion immediately before at least one of the non-curved portions 102α located on the terminal end side of the electrode with separator 100). That is, the single electrode with separator 100 has a plurality of electrodes arranged apart from each other as its constituent elements, and among the plurality of electrodes, the double-sided electrode is arranged at the terminal end portion of the electrode with separator 100. On the other hand, a single-sided electrode is arranged at a portion closest to the terminal end portion of the electrode with separator 100. More specifically, the single-sided electrode, which is a component of the single separator-attached electrode 100, is positioned between the double-sided electrode and the other double-sided electrode. Therefore, when the single electrode 100 with a separator is heat-treated during manufacturing, at least double-sided electrodes that are less likely to cause warpage stress are located on both sides of the portion that becomes the single-sided electrode, so that the single-sided electrode is located between the double-sided electrodes. It is possible to suppress the warp stress that may occur in the electrodes. Therefore, even when the portion of the long electrode 100 with a separator that becomes a single-sided electrode is positioned in the outermost region of the electrode assembly 200, the separator between the long-shaped electrode 100 and the double-sided electrode in the inner region of the electrode assembly 200 is applicable. The single-sided electrode can be suitably bonded as a whole. Therefore, the single-sided electrode as the outermost layer electrode can suitably function as a component of the electrode assembly 200. As a result, the secondary battery including the electrode assembly 200 as a whole can suitably exhibit desired battery characteristics.

This aspect is more preferable in the following points. Specifically, even when the above-mentioned electrode 100 with a separator has a meandering shape as a whole or has a shape of winding in one direction, a single-sided electrode is formed on a non-curved portion of the outermost region of the electrode 100 with a separator. Is possible to form. In this case, it is effective in that the other short electrode extending in one direction, which directly causes the generation of warping stress, cannot be positioned. However, in this case, since the single-sided electrode is positioned at the non-curved portion on the terminal end side of the electrode with separator 100, the portion that becomes the single-sided electrode during the heat treatment during the production of the single electrode with separator 100. Double-sided electrodes that are less likely to cause warpage stress are not located on both sides of the. On the other hand, in this embodiment, as described above, since the single-sided electrode is positioned between the one-sided electrode at the end of the long electrode with separator 100 and the other double-sided electrode, the single-sided electrode It is possible to effectively suppress the warpage stress that is likely to occur in the above-mentioned single-sided electrode by the double-sided electrode that is located on both sides of the single-sided electrode and is unlikely to generate warp stress. From the above, this aspect is advantageous in that the warping stress that may occur in the single-sided electrode can be more preferably suppressed. In the electrode with separator 100, when the single-sided electrode is positioned between one double-sided electrode at the end of the long electrode 100 with a separator and the other double-sided electrode of "plurality", warpage stress is unlikely to occur. Due to the "plurality" of the other double-sided electrode, the warpage stress that can occur in the single-sided electrode can be suppressed even more preferably. In this respect, the presence of "plurality" of the other double-sided electrode is particularly advantageous because the warping stress that can occur in the single-sided electrode can be further suppressed.

[Method for manufacturing the secondary battery of the present invention]
Hereinafter, the method for manufacturing the secondary battery of the present invention will be described. Specifically, a method for manufacturing a secondary battery including a single electrode with a separator having the above characteristics (one electrode and a separator forming an integral structure) and at least two other electrodes will be described. ..

As described in detail below, the manufacturing method of the present invention includes locally bending an elongated electrode 100 with a separator extending in one direction. In particular, in the manufacturing method of the present invention, a current collector (for example, a negative electrode current collector 11B) and a separator 50 of one electrode (for example, a negative electrode 10B) are formed on a portion 101 where a long electrode with a separator 100 is locally curved. It is characterized in that only is positioned (see FIG. 5). In other words, the electrode material layer (for example, the negative electrode material layer 12B) does not exist in the portion 101 that locally curves the long electrode with separator 100. When the electrode 100 with a separator is viewed as a whole, only the negative electrode current collector 11B and the separator 50 included in the electrode 100 with a separator form a continuous form as a whole.

In the manufacturing method of the present invention, the electrode material layer (for example, the negative electrode material layer 12B) does not exist in the curved portion 101 of the electrode with a separator, and therefore, due to this, the electrode material layer is locally cracked in the curved portion 101. It is possible to suitably suppress the occurrence of peeling and peeling. Thereby, the original technical problem found by the present inventor can be solved. Details including other technical effects will be described below.

More specifically, in the manufacturing method of the present invention, "(i) the electrode 100 with a separator alternately has a non-curved portion 102 and a curved portion 101 continuous with the non-curved portion 102, and (ii) a non-curved portion. The long electrode with a separator 100 is locally curved so that the 102 and the other electrode (for example, the positive electrode 10A) are alternately arranged along the stacking direction (see FIG. 5). _{Further, the long electrode with a separator 100 is locally curved so that the side portion 10A 1 of} the other electrode (for example, the positive electrode 10A) and the curved portion 101 face each other (see FIG. 5). The non-curved portion 102 of the electrode 100 with a separator formed by such local curvature serves as an electrode material layer forming portion of one electrode (for example, the negative electrode 10B), and is a current collector and a current collector of one electrode. The electrode material layers formed on both sides will be included. On the other hand, the electrode material layer (for example, the negative electrode material layer 12B) does not exist in the portion 101 (corresponding to the curved portion) in which the elongated electrode 100 with a separator is locally curved.

The elongated electrode 100 with a separator can be formed through the following basic steps (FIGS. 6A (a) to 6C (a) and 6A (b) to 6C (b)). reference).

Specifically, prior to locally curving the long electrode 100 with a separator, (i) the raw material of the electrode material layer 12B is intermittently applied to at least one main surface of the metal foil to be the current collector 11B. To form one long electrode (for example, negative electrode 10B), and (ii) thermocompression bonding the separator 50 so as to sandwich the electrode material layer 12B. This makes it possible to form an electrode 100 with a long separator. More specifically, in the step (i) above, after the raw material of the electrode material layer 12B is intermittently applied to the metal foil, a portion (for example, an electrode tab) that can be connected to the current collector 11B and the reed). The metal leaf may be cut to form one elongated electrode (without separator) (see FIGS. 6A and 6C).

In the embodiment shown in FIG. 6A, the electrode tab 20B _1, which is a portion that can be connected to the reed, is installed at the following location. An example is taken in which a long-shaped electrode 100 with a separator is formed and then locally curved to form a zigzag-shaped electrode 100 with a separator. _{In this case, the electrode tab 20B 1} is positioned on each of the plurality of non-curved portions of the zigzag-shaped electrode 100 with a separator, and each electrode tab 20B ₁ overlaps with one of the elongated electrodes before bending. The electrode tab 20B ₁ is positioned in this portion.

The location where the electrode tab is installed is not limited to the mode shown in FIG. 6A. For example, the embodiments shown in FIGS. 6B and 6C can be adopted. _{Specifically, as shown in FIG. 6B, the tab 20B 2} is substantially continuous with all the longitudinal side portions of the current collector 11B and is located outside the longitudinal side portion of the separator 50 in a plan view. May be served. Taking the case of finally forming the zigzag-shaped separator-attached electrode 100 as an example, as shown in FIG. 6C, the electrode is formed on only one of a plurality of non-curved portions of the zigzag-shaped separator-attached electrode 100. as tab 20B ₁ is positioned, the electrode tabs 20B ₁ is positioned in a portion comprising a curved front of the elongated one electrode.

In any of the embodiments shown in FIGS. 6A to 6C, the tab of the electrode with a zigzag-shaped separator after bending and the tab of the other short electrode extending in only one direction are from the viewpoint of preventing a short circuit. It is preferable that they are positioned so as not to overlap each other.

It can be said that the curved portion 101 is a portion where tensile stress can be generated due to the curved form. However, in the manufacturing method of the present invention, the electrode material layer is not formed on the curved portion 101. Therefore, it is possible to suppress the occurrence of tensile stress in the electrode material layer at the curved portion 101. By suppressing the generation of tensile stress on the electrode material layer, it is possible to suitably suppress the occurrence of local cracking or peeling of the electrode material layer at the curved portion 101. As a result, it is possible to suitably suppress the occurrence of a short circuit when a voltage is applied, starting from the cracked portion of the electrode material layer and / or the peeled portion of the electrode material layer.

Further, if the curved portion 101 of the electrode with separator 100 does not have an electrode material layer (for example, a negative electrode material layer), the volume of the electrode is reduced as a whole as compared with the case where the electrode material layer is also provided to the curved portion 101. .. From another point of view, it can be said that the separator 50 is a non-rigid material due to its material properties, so that the thickness of the curved portion 101 can be relatively reduced by the absence of the electrode material layer. .. As already described in the column of the characteristic portion of the secondary battery of the present invention, in the present invention, it is possible to provide a predetermined battery capacity even if the curved portion 101 does not have an electrode material layer (for example, a negative electrode material layer). .. Therefore, if it is possible to reduce the volume or thickness of the electrode 100 with a separator as a whole, it is possible to increase the battery capacity per unit volume due to this. That is, it is possible to further improve the energy density of the battery due to the increase in the battery capacity per unit volume.

The production method of the present invention may take the following aspects.

As described above, in the manufacturing method of the present invention, a current collector (for example, a negative electrode current collector 11B) of one electrode (for example, a negative electrode 10B) is formed on a portion 101 where a long electrode with a separator 100 is locally curved. And only the separator 50 is positioned (see FIG. 5). On the premise of such a feature, for example, the embodiments shown in FIGS. 7 and 8 may be adopted.

Specifically, meandering the long electrode with a separator 100 and arranging the other electrode (for example, the positive electrode 10A) on the non-curved portion 102 of the electrode 100 with a separator are alternately repeated (FIGS. 7 and 7). 8). Although the non-curved portion 102 is shown in a simplified manner in FIGS. 7 and 8, in detail, the non-curved portion 102 is a separator positioned on one electrode (for example, the negative electrode 10B) and both main surfaces of the electrode. It has a structure including 50. The one electrode (for example, the negative electrode 10B) includes a current collector (for example, a negative electrode current collector) and an electrode material layer (for example, a negative electrode material layer) formed on at least one main surface of the current collector. Considering this point, more specifically, after the long-shaped separator-attached electrode 100 is meandered, it is substantially directly above the negative electrode material layer which is a component of the non-curved portion 102 of the electrode that can be formed by meandering. Place the other electrode in the region.

By repeating the above steps, the non-curved portion 102 of the separator-equipped electrode 100 and the other electrode (for example, the positive electrode 10A) can be alternately arranged along the stacking direction. As a result, it is finally possible to obtain an electrode assembly in which a plurality of electrode constituent layers including a positive electrode 10A, a negative electrode 10B, and a separator 50 between the positive electrode 10A and the negative electrode 10B are laminated. When the electrode assembly is enclosed in the exterior body together with the electrolytic solution, the secondary battery of the present invention can be finally obtained.

As described above, the separator 50 is a porous member. Therefore, the position of the negative electrode material layer located below the separator 50 is determined through the hole of the separator 50, which is a component of the non-curved portion 102 of the electrode, which can be formed after the long electrode with the separator 100 is meandered. It is possible to confirm favorably. From the above, when the other electrode (for example, the positive electrode 10A) is arranged on the non-curved portion 102, the other electrode can be suitably positioned in a region substantially directly above the negative electrode material layer of the non-curved portion 102. Is. That is, it is possible to suitably suppress the misalignment of the other electrode.

Further, the following aspects may be adopted without being limited to the embodiments shown in FIGS. 7 and 8.

Specifically, the long electrode with a separator is wound in one direction, and the other electrode is arranged in the non-curved portion of the electrode with a separator. As a result, the non-curved portion of the electrode with the separator and the other electrode are alternately arranged along the stacking direction, while only the current collector (for example, the negative electrode current collector) and the separator of one electrode (for example, the negative electrode 10B) are entirely arranged. A structure that winds in one direction may be formed (see FIG. 3). As described above, it is finally possible to obtain an electrode assembly in which a plurality of electrode constituent layers including a positive electrode 10A, a negative electrode 10B, and a separator 50 between the positive electrode 10A and the negative electrode 10B are laminated. When the electrode assembly is enclosed in the exterior body together with the electrolytic solution, the secondary battery of the present invention can be finally obtained.

The production method of the present invention preferably adopts the following aspects.

Specifically, in this embodiment, it is preferable to form the electrode assembly 200 having the following characteristics (see FIG. 4).
The other electrode 10A of the single-sided electrode structure extending in only one direction is not positioned as the outermost layer electrode which is a component of the obtained electrode assembly 200.
On the other hand, as the outermost layer electrode which is a component of the obtained electrode assembly 200, the electrode 10B having a single-sided electrode structure which is a component of the electrode with separator 100 is positioned. Specifically, the portion of the electrode with separator 100 that becomes the non-curved portion 102α (the portion located on the terminal end side of the electrode with separator 100) obtained through the following steps (1) and (2) is defined as a double-sided electrode structure. To do. On the other hand, the non-curved portion 102β of the separator-attached electrode 100 located in the outermost region of the electrode assembly 200 (the portion in front of at least one of the non-curved portions 102α located on the outermost end side of the separator-equipped electrode 100) is “one side”. "Electrode structure".

In order to form the electrode assembly having the above characteristics, it is preferable to go through the following steps.

(1) Not only is the raw material of the electrode material layer intermittently coated on both main surfaces of the sheet-shaped metal foil to be the current collector to form one electrode of the double-sided electrode structure, but it also becomes the current collector. The raw material of the electrode material layer is locally applied only to one main surface of the sheet-shaped metal foil to form one electrode having a single-sided electrode structure (see FIG. 6D). In particular, in this embodiment, one side of the sheet-shaped metal foil is adjacent to a portion where the raw material of the electrode material layer is applied to both main surfaces of at least one end region to form one electrode of the double-sided electrode structure. One electrode of the electrode structure is formed. From the above, a long (or sheet-like) electrode 100 with a separator can be obtained. In addition, "the formation of one electrode of the single-sided electrode structure adjacent to the portion where the one electrode of the double-sided electrode structure is formed" is a component of the obtained elongated electrode with a separator 100. This means forming an electrode 10B having a single-sided electrode structure that is closest to and separated from the electrode 10B having a double-sided electrode structure located on the terminal end side of the elongated electrode with a separator 100 among a plurality of electrodes. ..

Although not particularly limited, in the embodiment shown in FIG. 6D, as in the embodiment shown in FIG. 6C, for example, a plurality of non-curved portions of the electrode 100 with a separator after curvature obtained through the step (2) below. as the electrode tabs 20B ₁ only one is positioned out of the electrode tabs 20B ₁ may be positioned in a portion comprising a curved front of the elongated one electrode.

(2) After the step (1) is carried out, the elongated electrode 100 with a separator is wound in one direction, and then the electrode 100 with a separator wound in one direction is meandered (see FIG. 4). In particular, in this embodiment, one electrode 100 with a long separator is provided so that one electrode having a single-sided electrode structure is positioned in the outermost region of the electrode assembly 200 composed of the electrode 100 with a separator and the other electrode. Wind in the direction. Next, the winding / meandering of the long electrode with a separator 100 and the placement of the other electrode on the non-curved portion 102 of the electrode 100 with a separator formed at the time of winding / meandering are alternately repeated. As a result, the electrode assembly 200 in which the non-curved portion 102 of the electrode with separator 100 and the other electrode are alternately arranged along the stacking direction can be formed.

In this embodiment, the single electrode with separator 100 has a plurality of electrodes arranged apart from each other as its constituent elements, and among the plurality of electrodes, the terminal portion of the electrode with separator 100 is a double-sided electrode. Is arranged, while the single-sided electrode is separately arranged at the portion closest to the terminal end portion of the electrode with separator 100. More specifically, the single-sided electrode, which is a component of the single separator-attached electrode 100, is positioned between at least one double-sided electrode and the other double-sided electrode. Therefore, during the heat treatment during the manufacture of the single electrode with separator 100, at least double-sided electrodes that are less likely to cause warpage stress are located on both sides of the portion that becomes the single-sided electrode. It is possible to suppress the warp stress that may occur. Therefore, even when the portion of the long electrode 100 with a separator that becomes a single-sided electrode is positioned in the outermost region of the electrode assembly 200, the separator between the long-shaped electrode 100 and the double-sided electrode in the inner region of the electrode assembly 200 is applicable. The single-sided electrode can be suitably bonded as a whole. Therefore, the single-sided electrode as the outermost layer electrode can suitably function as a component of the electrode assembly 200.

From the viewpoint that not only one outermost layer electrode but also the other outermost layer electrode functions suitably as a component of the electrode assembly 200, in the step (1) above, "both" of the sheet-shaped metal foil It is preferable to form one electrode of the single-sided electrode structure adjacent to a portion where the raw material of the electrode material layer is applied to both main surfaces of the end region to form one electrode of the double-sided electrode structure.

Although one embodiment of the present invention has been described above, it merely illustrates a typical example of the scope of application of the present invention. Therefore, those skilled in the art will easily understand that the present invention is not limited to this, and various modifications can be made.

The secondary battery according to the embodiment of the present invention can be used in various fields where storage is expected. Although only an example, the secondary battery according to the embodiment of the present invention, particularly the non-aqueous electrolyte secondary battery, is used in the fields of electricity, information, and communication (for example, mobile phones, smartphones, notebooks, etc.) in which mobile devices and the like are used. Mobile device fields such as personal computers and digital cameras), home / small industrial applications (eg, power tools, golf carts, home / nursing / industrial robot fields), large industrial applications (eg forklifts, elevators, bay ports) Crane field), transportation system field (for example, hybrid vehicle, electric vehicle, bus, train, electric assist bicycle, electric motorcycle, etc.), power system application (for example, various power generation, road conditioner, smart grid, general household installation) It can be used in fields such as smart power storage systems) and in space / deep sea applications (for example, fields such as space probes and submersible research vessels).

200 Electrode assembly 100, 100'Electrodes with separator 101, 101'Curved part of electrode with separator 102, 102α, 102β Non-curved part of electrode with separator 50, 50' Separator 10A, 10A'Positive electrode (other electrode)
10A ₁ Side of positive electrode (side of other electrode)
10B, 10B'negative electrode (one electrode)
11A, 11A'Positive current collector 11B, 11B'Negative electrode current collector 12A, 12A'Positive material layer 12B, 12B'Negative electrode material layer 20B ₁ Electrode tab 20B ₂ Electrode tab corresponding part α'Curved part of electrode with separator Cracked portion of the electrode material layer in X winding region Y meandering region

Claims (20)

A secondary battery comprising a single electrode with a separator in which one electrode and a separator form an integral structure, and at least two other electrodes having different polarities from the one electrode.
The electrode with a separator alternately has a non-curved portion and a curved portion continuous with the non-curved portion, the non-curved portion and the other electrode are alternately arranged along a stacking direction, and the curved portion is respectively. A secondary battery having only a curved current collector of one of the electrodes and the separator. The secondary battery according to claim 1, wherein only the current collector and the separator of the one electrode included in the electrode with a separator are continuous as a whole. The secondary battery according to claim 1 or 2, wherein the curved portion of the electrode with a separator is a portion where the electrode material layer is not formed on one of the electrodes. The secondary battery according to any one of claims 1 to 3, wherein only the current collector and the separator of the one electrode form a meandering form as a whole. The secondary battery according to any one of claims 1 to 3, wherein only the current collector and the separator of the one electrode are wound in one direction as a whole. The electrode with a separator includes a winding region formed by winding in one direction and a meandering region continuous with the winding region by the curved portion and the non-curved portion of the electrode with a separator. Configure and
The winding region is positioned in the outermost region of the electrode assembly composed of the electrode with a separator and the other electrode.
The secondary battery according to any one of claims 1 to 3, wherein the outermost layer electrode having a single-sided electrode structure is positioned in the non-curved portion of the winding region of the electrode with a separator. The secondary battery according to any one of claims 1 to 6, wherein at least one side portion of the other electrode and the curved portion of the electrode with a separator face each other. Claim 1 in which the electrodes with separators have two separators facing each other, and in the curved portion, only the current collector of the one electrode is positioned between the two separators. The secondary battery according to any one of 7 to 7. The non-curved portion of the electrode with a separator serves as an electrode material layer forming portion of the one electrode, and the current collector of the one electrode and the electrode formed on at least one side of the current collector. The secondary battery according to any one of claims 1 to 8, which includes a material layer. The secondary battery according to any one of claims 1 to 9, wherein the one electrode and the other electrode have a layer capable of storing and releasing lithium ions. A method for manufacturing a secondary battery, comprising an electrode with a separator in which one electrode and a separator form an integral structure, and at least two other electrodes having different polarities from the one electrode.
Including locally curving the elongated electrode with separator extending in one direction.
A manufacturing method in which only the current collector of one of the electrodes and the separator are positioned at a portion where the elongated electrode with a separator is locally curved. The manufacturing method according to claim 11, wherein only the current collector and the separator of the one electrode included in the electrode with a separator are continuous as a whole. The elongated electrode has a non-curved portion and a curved portion continuous with the non-curved portion alternately, and the non-curved portion and the other electrode are alternately arranged along the stacking direction. The manufacturing method according to claim 11 or 12, wherein the electrode with the separator is locally curved. Prior to locally curving the elongated electrode with a separator,
The raw material of the electrode material layer is intermittently coated on at least one main surface of the metal foil to be the current collector to form one long electrode, and the separator is sandwiched so as to sandwich the electrode material layer. The production method according to any one of claims 11 to 13, which comprises forming the elongated electrode with a separator by thermocompression bonding. The manufacturing method according to claim 14, wherein the portion where the elongated electrode with a separator is locally curved is a non-coated portion of the raw material of the electrode material layer. The non-curved portion of the electrode with a separator is an electrode material layer forming portion of the one electrode, and the current collector of the one electrode and the electrode material layer formed on at least one side of the current collector. 13. The manufacturing method according to claim 13. By alternately repeating the meandering of the elongated electrode with a separator and the arrangement of the other electrode on the non-curved portion of the electrode with a separator formed during the meandering, the electrode with a separator The manufacturing method according to any one of claims 11 to 16, wherein the non-curved portion and the other electrode are alternately arranged along the stacking direction. The electrode with a separator is formed by winding the elongated electrode with a separator in one direction and arranging the other electrode on the non-curved portion of the electrode with a separator formed at the time of winding. The production method according to any one of claims 11 to 16, wherein the non-curved portion and the other electrode are alternately arranged along the stacking direction. The elongated electrode with a separator is wound in one direction, and then the electrode with a separator is meandered, and the other is formed on the non-curved portion of the electrode with a separator formed during the winding and the meandering. By alternately repeating the arrangement of the electrodes of the above, the non-curved portion of the electrode with the separator and the other electrode are alternately arranged along the stacking direction.
The elongated electrode with a separator is wound in one direction so that the one electrode having a single-sided electrode structure is positioned in the outermost region of the electrode assembly composed of the electrode with a separator and the other electrode. The production method according to any one of claims 11 to 16. When forming the elongated electrode with a separator, the raw material of the electrode material layer is locally applied only to one main surface of the metal foil serving as a current collector to obtain the one electrode having the single-sided electrode structure. The portion to be formed is adjacent to the portion where the raw material of the electrode material layer is locally coated on both main surfaces of at least one end region of the metal foil to form the one electrode of the double-sided electrode structure. 19. The manufacturing method according to claim 19.

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